1. Field of the Invention
The present invention generally relates to conveyor belts and, more particularly, to modular conveyor belts formed of rows of plastic belt modules pivotally interlinked by transverse pivot rods. Preferably, the modules are of polymeric materials of microcellular foams including additives. Methods for the production of such modules are also described.
2. Prior Art
Because they do not corrode, are light weight, and are easy to clean, plastic modular conveyor belts are gaining increased usage in a wide range of industrial applications. Modular conveyor belts are built from molded plastic modular links, or modules, arranged side-by-side in rows of a selected width. A series of spaced apart link ends extending from each side of the modules include aligned openings that receive a pivot rod. The link ends along one end of a row of modules are interconnected with the link ends of an adjacent row. The pivot rod journaled in the aligned openings of the side-by-side and end-to-end connected modules form a hinge between adjacent rows. Rows of belt modules are connected together to form an endless conveyor belt capable of articulating about drive sprockets positioned at opposite ends of the conveying surface.
Modules for modular conveyor belts are typically formed of polyolefinic materials, for example, polypropylene or polyethylene. A modular conveyor belt system typically comprises a support frame upon which the conveyor belt rests as drive sprockets spaced at intervals along the belt length provide a motive force. A preferred material for modules is high density polyethylene having a density in excess of 0.94 g/cm3. When the weight of the conveyor belt becomes too great, the drive sprockets and other support frame components, and even the belt modules themselves, experience excessive wear and must be replaced. Therefore, belt and support structure longevity can be an important factor in a customer deciding to continue using one manufacture over another.
In that light, the modules of the present invention are of polymeric foams having a plurality of voids, called cells, in the polymeric matrix. By replacing solid plastic with voids, such microcellular polymeric foams use less raw material than solid plastics for a given volume. The modules of the present invention comprising microcellular polymeric foams instead of solid plastics are less expensive in terms of material costs and are of a comparatively reduced weight. This latter attribute translates to a conveyor belt having a weight reduction of about 30% in comparison to a similarly sized belt of a solid polymeric material. A belt of reduced weight leads to prolonged module wear and prolonged conveyor belt support structure service.